A hunt for polluters who release organic refuse into the Periyar, which affects the Dissolved Oxygen (DO) level of the river system, will begin shortly.

The State Pollution Control Board (PCB) is planning to carry out extensive surveys along the banks of some of the streams and major canals that run into the river for identifying the polluters. Organic waste is suspected to be reaching the river system in large quantities, leading to reduced DO levels in the river. The issue of reduced DO was noticed last year, said K. Sajeevan, chairman of the PCB.

Reduced levels of DO would affect the aquatic life in a water body. Periyar is also one of the major drinking water sources for the district.

The commercial buildings and high rises in the region will be surveyed for identifying the culprits. Dumping of domestic waste into the water body could be one of the main reasons for the reduced DO, which needs to be curbed, he said.

The physical verification of the buildings would help ascertain whether organic waste was discharged from them into the river system, Ms. Sajeevan said.

The board is also working on a proposal for cleaning up the canals, namely, Edapallythodu that is connected to Periyar for improving the water quality of the river system.

The agency was willing to cooperate with local bodies, including the Kochi Corporation and the Kalamassery Municipality, in this effort and discussions would be held with them shortly, he said.

At the same time, environmentalists felt the board’s move was a complete hogwash as there was no significant dumping of organic refuse from households and commercial buildings. Instead, some of the major industrial units situated on the banks of the river were letting out organic refuses in large quantities, they pointed out.

C.M. Joy, executive committee member of the Aluva Paristhithi Samrakshana Samity, said there might be some stray cases of households dumping organic refuse in the river.

One should not overlook the release of organic waste in large quantities by industrial houses on the river bank and bakery units. Pollution caused by the cleaning of lorries in the river and dumping of septage by tanker lorries too should be taken into account, he said Dr. Joy was critical of the PCB’s stand towards the industrial units that were polluting the river system.

Release of refuse from some of the industrial estates in the area was reaching the river system. The dissolved oxygen level was unlikely to go down this season as there was enough water in the river system sufficient for diluting the pollutants, he said.

Sunny George, a water management expert, felt the reduced DO of a river system could be the combined result of a series of complex factors, including release of organic waste.

It would not be appropriate to jump to a conclusion without analysing the contributing factors, he said.

Last year, large tracts of forest were gutted during the summer season. Ash from the burning of forest would certainly reach the system. Industrial units would have a major role in reducing the DO considering the volume of the effluents they release.

Reduced water flow in the system can also contribute to the change in water chemistry. Extensive studies needed to be conducted for isolating the factor that was defining the DO of Periyar, Dr. George said.